The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 47

  1. 58. What is mastocytic enterocolitis?

A high powered field (hpf) is what you see through a microscope when you use powerful magnifying lenses. With very few exceptions, high powered fields using the same lenses are the same size. Since they are the same size, you can directly compare results from various groups all over the world.

In 2006, a paper was published that coined the term “mastocytic enterocolitis”. The author described mastocytic enterocolitis as more than 20 mast cells per high powered field. This paper was about people with severe chronic diarrhea that did not improve with treatment. The author found that healthy people had about 13 mast cells/hpf while people with severe chronic diarrhea had about 20 mast cells/hpf. The author felt that the extra mast cells were responsible for the diarrhea and inflammation so they called the extra mast cells in the colon and the small intestine “mastocytic enterocolitis”. Enterocolitis is the term for inflammation in the small intestine and colon.

The author felt that 20 mast cells/hpf was the cutoff between a normal amount of mast cells in the GI tract and an abnormal amount. Under 20 was considered normal while 20 and above was considered abnormal. However, there have been a number of papers since that look at how many mast cells are present in the GI tract for patients with different conditions as well as healthy people. There are several conditions that can cause you to have 20 or more mast cells/hpf. (I wrote an exhaustive series on this in 2015-2016. Links are below.)

Additionally, in some situations, people have over 20 mast cells/hpf without having any symptoms. Sometimes healthy people without any GI conditions have over 20 mast cells/hpf. For this reason, there is not agreement about how many mast cells in the GI tract is too many. (If you’re looking for my opinion, I think the number for what is too many is around 25-30/hpf. This is just my opinion.)

In the last several years, some doctors have begun linking mastocytic enterocolitis to mast cell disease. This makes sense because we know that in those people, mast cell inflammation drives GI symptoms and damage. Mast cell patients certainly have a lot of inflammation in the GI tract so having extra mast cells there makes sense. Some experts think that mastocytic enterocolitis is a sign of mast cell activation syndrome and that patients with mastocytic enterocolitis all have mast cell activation syndrome.

Mastocytic enterocolitis is absolutely a real phenomenon. In these people, mast cells cause a lot of GI symptoms and damage the GI tract. Experts have not all agreed upon whether or not everyone with mastocytic enterocolitis has mast cell disease. Also, there are some researchers that feel that mastocytic enterocolitis is actually its own mast cell disease rather than just a feature of another mast cell disease like mast cell activation syndrome.

Currently, mastocytic enterocolitis is not recognized by the WHO as its own disorder. However, that could certainly change. It was only last year that MCAS was recognized by the CDC even though it was routinely recognized by researchers and providers. (Author’s note: This was initially published stating that the WHO recognized MCAS, rather than the CDC. MCAS has not yet been recognized by the WHO. This is a whopper mistake on my part. Many thanks to the reader who saw this. Sorry!) I personally expect this to change in the next few years as more mast cell patients are diagnosed and mastocytic enterocolitis is better recognized. I think it is suggestive of mast cell disease but I also think providers need to eliminate other possible causes for the extra mast cells in the GI tract.

For more detailed information, please visit these posts:

Mast cells in the GI tract: How many is too many? (Part One)

Mast cells in the GI tract: How many is too many? (Part Two)

Mast cells in the GI tract: How many is too many? (Part Three)

Mast cells in the GI tract: How many is too many? (Part Four)

Mast cells in the GI tract: How many is too many? (Part Five)

Mast cells in the GI tract: How many is too many? (Part Six)

Mast cells in the GI tract: How many is too many? (Part Seven)

Mast cells in the GI tract: How many is too many? (Part Eight)

Mast cells in the GI tract: How many is too many? (Part eight)

One study assessed whether mast cell count would be influenced depending on which part of the organ biopsies were taken from. While the difference in count was not large, it is worth considering that these counts all straddle the cut off of 20 mast cells/hpf.  This means that patients with the same GI symptoms could have biopsies with over or under 20/hpf depending on the site of the biopsy.  See Table 24 for details.

Table 24: Effect of sampling site on mast cell count/hpf in colon of chronic diarrhea patients
Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gastroenterol 2012; 18 (5): 322-326.
Microscopy method: 400x magnification, mast cells counted in 5 hpf and averaged
Visualization: Tryptase (IHC), toluidine blue
Rectum Sigmoid Descending colon Transverse colon Ascending colon Cecum
20.5±5 18.3±3.5 22.6±3.9 20.7±4.9 25.5±6.7 22.1±4.9

 

The same paper also looked at effect of season on mast cell count.  There was no significant difference, but again, the range of biopsies in each season straddles the 20/hpf line. See Table 25 for details.

Table 25: Effect of season on mast cell count in colon of diarrhea patients
Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gastroenterol 2012; 18 (5): 322-326.
Microscopy method: 400x magnification, mast cells counted in 5 hpf and averaged
Visualization: Tryptase (IHC), toluidine blue
Spring Summer Fall Winter
20.6±4.7 24.2±4.9 19.5±3.9 20.3±4.9

 

The most telling portion of this study compared mast cell counts when using a simple stain (toluidine blue) and when using IHC (antibody for tryptase) to find mast cells in biopsies.  Mast cells are not easy to see on biopsy.  They require special stains, and even then, they are hard to see.  Immunohistochemistry (IHC) uses antibodies to identify markers on cells that are easier to see with a microscope.  It is not uncommon for unfamiliar doctors to refuse the use of IHC testing (which usually includes CD117, CD25, CD2 or tryptase) in lieu of commonly available stains in the lab.  However, even stains that visualize mast cells are inferior to IHC methods.  In biopsies taken from all parts of the colon, toluidine blue staining showed less than half of the mast cells visualized using IHC for tryptase.  This means that when IHC testing isn’t ordered, counts reported by simple staining are much lower than the true count. See Table 26 for details.

Table 26: Comparison of mast cell count in biopsies stained with toluidine blue and with tryptase antibody (IHC)
Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gastroenterol 2012; 18 (5): 322-326.
Microscopy method: 400x magnification, mast cells counted in 5 hpf and averaged
Visualization: Tryptase (IHC) and toluidine blue
Staining method Rectum Sigmoid Descending colon Transverse colon Ascending colon Cecum
IHC 20.5±5 18.3±3.5 22.6±3.9 20.7±4.9 25.5±6.7 22.1±4.9
Toluidine blue 8.5±0.7 6.8±1.2 10.3±4.2 10.3±3.5 12.5±5 8.1±2.9
% of cells identified by IHC seen by toluidine blue staining 41% 37% 46% 50% 49% 37%

 

There are other factors that contribute to lack of consensus in mast cell counts in GI tissue. One of the biggest causes is that not all labs use standard size high powered fields.  HPF is usually 0.25mm2, but it is not uniform throughout the research world.  Many papers don’t even provide the size of their high powered fields.  More than that, many papers report mast counts per mm2 without providing conversion factors so it’s not always possible to compare results from one paper to another.  There were some papers I wanted to use for this series that I couldn’t because I couldn’t be sure that I could convert their mast cells/mm2 confidently to mast cells/hpf.

Together with the fact that number of hpf counted, methods of biopsy slide preparation, stains and IHC antibodies are variable, it is hard to get a real understanding of whether the cut off of 20 mast cells/hpf is meaningful.  It is my finding that there are a number of conditions that cause mast cells/hpf to be higher than controls in an experiment.  It is also my finding that in some experiments, control subjects have baseline mast cell counts over 20 mast cells/hpf. It is reasonable to assume that inflammatory GI conditions can cause mast cell hyperplasia.  But the fact that chronic urticaria patients often have mast cell counts higher than control subjects is also telling.  It speaks to the fact that an allergic process can elevate mast cell counts in a space where there is no appreciable symptomology. If patients have reactions to “pseudoallergens” as described in that paper, then it is possible that these reactions could drive the increase in mast cell count in the GI tract.  If this is true, then the many mast cell patients who have “pseudoallergen” responses could see an increase in GI mast cell burden as a result of their mast cell disease.

References:

Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.

Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.

Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168,

Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.

Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.

Ramsay DB, et al. Mast cells in gastrointestinal disease. Gastroenterology & Hepatology 2010; 6 (12): 772-777.

Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gatroenterol 2012; 18 (5): 322-326.

Walker MM, et al. Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia. Aliment Pharmacol Ther 2009; 29 (7): 765-773.

Hahn HP, Hornick JL. Immunoreactivity for CD25 in Gastrointestinal Mucosal Mast Cells is Specific for Systemic Mastocytosis. American Journal of Surgical Pathology 2007; 31(11): 1669-1676.

Vivinus-Nebot M, et al. Functional bowel symptoms in quiescent inflammatory bowel diseases : role of epithelial barrier disruption and low-grade inflammation. Gut 2014; 63: 744-752.

Minnei F, et al. Chronic urticaria is associated with mast cell infiltration in the gastroduodenal mucosa. Virchows Arch 2006; 448(3): 262-8.

Hamilton MJ, et al. Mast cell activation syndrome: A newly recognized disorder with systemic clinical manifestations. J Allergy Clin Immunol 2011; 128: 147-152.

Barbara G, et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology 2004; 126(3): 693-702.

Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.

Afrin LB, Molderings GJ. A concise, practical guide to diagnostic assessment for mast cell activation disease. World J Hematol 2014; 3 (1): 1-17.

Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

Akin C, et al. Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol 2010; 126 (6): 1099-1104.

Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol 2012: 157 (3): 215-225.

Mast cells in the GI tract: How many is too many? (Part seven)

The 2014 Doyle paper provides mast cell counts in colon biopsies for healthy controls, MCAS, and IBS. Mast cells were identified using antibodies for tryptase, CD117, CD25 and CD30 (IHC). Mast cells were counted in both one HPF in the densest portion of the slide and in five HPF and averaged.  In the densest portion of the slide, mast cell counts were higher in 1 HPF than in the average of 5 HPF.  Differences in methodology such as this can contribute to lack of consensus on what constitutes too many mast cells. See Table 21 for details.

Table 21: Comparison of mast cell count in 1 HPF and in the average of 5 HPF
Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.
Microscopy method: 400x magnification, mast cells counted in 1 hpf
Visualization: IHC for tryptase, CD117, CD25 and CD30
HPF Control group A:

Healthy controls

Control group B:

MCAS

Control group C:

IBS

Average Range Average Range Average Range
Average of 5 hpf 19 mast cells/hpf 7-39 mast cells/hpf 20 mast cells/hpf 12-31 mast cells/hpf 23 mast cells/hpf 9-45 mast cells/hpf
1 hpf 26 mast cells/hpf 11-55 mast cells/hpf 28 mast cells/hpf 14-48 mast cells/hpf 30 mast cells/hpf 13-59 mast cells/hpf

 

Other papers also investigated factors that could contribute to differences in mast cell counts. The 2015 Sethi paper evaluated differences in GI mast cell counts between men and women.  Women had  marginally higher counts in both IBS and control groups. See Table 22 for details.

Table 22: Difference in mast cell count between men and women with chronic diarrhea and asymptomatic controls
Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.
Microscopy method: 400x magnification, mast cells counted in 5 hpf and averaged
Visualization: CD117 (IHC)
Sample type Study group: Women Study group: Men Control group: Women Control group: Men
Colon Average Range Average Range Average Range Average Range
30 mast cells/hpf 27-34 mast cells/hpf 27 mast cells/hpf 24-31 mast cells/hpf 24 mast cells/hpf 22-37 mast cells/hpf 21 mast cells/hpf 19-24 mast cells/hpf
Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters.

 

One paper looked at the difference in mast cell count in the rectum of healthy patients over the age of 55 and under.  Please note that these counts were made using a much lower magnification than other papers in this series, so mast cell counts are not directly comparable. Mast cells were identified using antibodies to tryptase (IHC). See Table 23 for details.

Table 23: Differences in GI mast cell count in healthy patients over and under 55 years of age.
Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.
SPECIAL NOTE: THESE COUNTS WERE MADE AT HALF THE MAGNIFICATION OF OTHER PAPERS IN THIS SERIES.  THESE MAST CELL COUNTS ARE NOT DIRECTLY COMPARABLE TO OTHER STUDIES.
200x magnification, number of hpf not explicitly stated, assumed mast cells counted in 1 hpf
Visualization: Tryptase (IHC)
Sample type Study group: Healthy, over 55 years old Study group: Healthy, under 55 years old Control group B:

No control group

Rectum Average Range Average Range Average Range
40.5 ± 2.4 mast cells/hpf 51.7 ± 4.1 mast cells/hpf N/A N/A

 

References:

Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.

Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.

Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168,

Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.

Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.

Ramsay DB, et al. Mast cells in gastrointestinal disease. Gastroenterology & Hepatology 2010; 6 (12): 772-777.

Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gatroenterol 2012; 18 (5): 322-326.

Walker MM, et al. Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia. Aliment Pharmacol Ther 2009; 29 (7): 765-773.

Hahn HP, Hornick JL. Immunoreactivity for CD25 in Gastrointestinal Mucosal Mast Cells is Specific for Systemic Mastocytosis. American Journal of Surgical Pathology 2007; 31(11): 1669-1676.

Vivinus-Nebot M, et al. Functional bowel symptoms in quiescent inflammatory bowel diseases : role of epithelial barrier disruption and low-grade inflammation. Gut 2014; 63: 744-752.

Minnei F, et al. Chronic urticaria is associated with mast cell infiltration in the gastroduodenal mucosa. Virchows Arch 2006; 448(3): 262-8.

Hamilton MJ, et al. Mast cell activation syndrome: A newly recognized disorder with systemic clinical manifestations. J Allergy Clin Immunol 2011; 128: 147-152.

Barbara G, et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology 2004; 126(3): 693-702.

Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.

Afrin LB, Molderings GJ. A concise, practical guide to diagnostic assessment for mast cell activation disease. World J Hematol 2014; 3 (1): 1-17.

Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

Akin C, et al. Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol 2010; 126 (6): 1099-1104.

Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol 2012: 157 (3): 215-225.

Mast cells in the GI tract: How many is too many? (Part Four)

The 2012 study by Akhavein that described allergic mastocytic enterocolitis also performed biopsies on the stomach of patients with a history of atopic/allergic disease were biopsied.  Mast cells were identified using an antibody to CD117, the CKIT receptor found on the surface of all mast cells. The cells were counted in only 1 hpf.  On average, there were 39 mast cells/hpf with a range of 16-82 mast cells/hpf.  These cells were also scattered and not clustered.  See Table 13 for details.

Table 13: Mast cell count in stomach of patients with GI pain and dysmotility and a history of allergic disease
Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.
Stomach Study group: atopic/allergic history with abdominal pain and GI dysmotility Control group A:

No control group

Control group B:

No control group

Average Range Average Range Average Range
39 mast cells/hpf 16-82 mast cells/hpf N/A N/A N/A N/A
Diffuse, scattered cells, no clusters.

 

A 2015 publication evaluated the mast cell count in patients with chronic diarrhea for unknown reasons.  Mast cells were quantified using an antibody to CD117.  Cells were only counted in 1 hpf in the portion of the slide with the most mast cells.  The healthy control group averaged 24 mast cells/hpf, while the study group with chronic diarrhea averaged 31 mast cells/hpf. See Table 14 for details.

Table 14: Mast cell count in colon of patients with chronic diarrhea
Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.
Microscopy method: 400x magnification, mast cells counted in 1 hpf
Visualization: CD117 and tryptase (IHC)
Sample type Study group: Chronic diarrhea Control group A:

Healthy controls

Control group B:

No control group

Colon Average Range Average Range Average Range
31 mast cells/hpf 24-34 mast cells/hpf 24 mast cells/hpf 22-27 mast cells/hpf N/A N/A
Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters.

 

References:

Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.

Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.

Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168,

Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.

Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.

Ramsay DB, et al. Mast cells in gastrointestinal disease. Gastroenterology & Hepatology 2010; 6 (12): 772-777.

Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gatroenterol 2012; 18 (5): 322-326.

Walker MM, et al. Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia. Aliment Pharmacol Ther 2009; 29 (7): 765-773.

Hahn HP, Hornick JL. Immunoreactivity for CD25 in Gastrointestinal Mucosal Mast Cells is Specific for Systemic Mastocytosis. American Journal of Surgical Pathology 2007; 31(11): 1669-1676.

Vivinus-Nebot M, et al. Functional bowel symptoms in quiescent inflammatory bowel diseases : role of epithelial barrier disruption and low-grade inflammation. Gut 2014; 63: 744-752.

Minnei F, et al. Chronic urticaria is associated with mast cell infiltration in the gastroduodenal mucosa. Virchows Arch 2006; 448(3): 262-8.

Hamilton MJ, et al. Mast cell activation syndrome: A newly recognized disorder with systemic clinical manifestations. J Allergy Clin Immunol 2011; 128: 147-152.

Barbara G, et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology 2004; 126(3): 693-702.

Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.

Afrin LB, Molderings GJ. A concise, practical guide to diagnostic assessment for mast cell activation disease. World J Hematol 2014; 3 (1): 1-17.

Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

Akin C, et al. Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol 2010; 126 (6): 1099-1104.

Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol 2012: 157 (3): 215-225.

Mast cells in the GI tract: How many is too many? (Part Two)

As I mentioned in the previous post, a 2006 paper counted mast cells in the duodenum (part of the small intestine) and colon of patients with treatment resistant chronic diarrhea and compared these counts to patients with known inflammatory GI diseases and to asymptomatic healthy controls.  This paper posited that cell counts over 20 mast cells/hpf represented a distinct phenomenon called mastocytic enterocolitis.  The author felt that mastocytic enterocolitis was distinct from inflammation caused by other GI diseases, such as Crohn’s colitis, ulcerative colitis and celiac disease.

In this paper, the counts for asymptomatic controls ranged from 3-20 cells/hpf and the counts for known inflammatory GI disease ranged from 2-18 mast cells/hpf.  Patients with chronic diarrhea that resisted treatment demonstrated counts ranging from 13-35 mast cells/hpf.  Mast cells were identified by using an antibody to tryptase.

70% of patients with chronic diarrhea without a known cause had over 20 mast cells/hpf. Cells were counted in 10 hpf and averaged.  Counting in multiple fields and averaging generally gives more representative counts. Based upon this study, it was reasonable to assume that mast cells over 20/hpf was higher than normal. See Table 4 for details.

Table 4: Mast cell counts in duodenum and colon of chronic diarrhea patients (Jakate 2006)
Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.
Microscopy method: 400x magnification, mast cells counted in 10 hpf and averaged
Visualization: Tryptase (IHC)
Sample type Study group: Intractible chronic diarrhea Control group A: Inflammatory GI disease that causes chronic diarrhea (ie. Crohn’s colitis, ulcerative colitis, gluten sensitive enteropathy) Control group B: Asymptomatic, healthy controls
Duodenum and colon (counts averaged) Average Range Average Range Average Range
25.7 mast cells/hpf 13-35 mast cells/hpf 12.4 mast cells/hpf 2-18 mast cells/hpf 13.3 mast cells/hpf 3-20 mast cells/hpf

 

In a 2012 paper by Akhavein, the stomach, small intestine and colon of patients with a history of atopic/allergic disease were biopsied.  Mast cells were identified using an antibody to CD117, the CKIT receptor found on the surface of all mast cells. The cells were counted in only 1 hpf.

This paper found that the average mast cell count for biopsies from all organs was 37/hpf.  The author posited that given that these patients had a history of allergic conditions, that a count of over 40/hpf described a phenomenon called allergic mastocytic gastroenteritis that was distinct from the previous described mastocytic enterocolitis.  Cells were scattered and not clustered. There was no control group in this study.  See Table 5 and Table 6 for details.

Table 5: Mast cell count in small intestine of patients with GI pain and dysmotility and a history of allergic disease
Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.
Microscopy method: Magnification not explicitly stated, assumed 400x, mast cells counted in 1 hpf
Visualization: CD117 (IHC)
Sample type Study group: atopic/allergic history with abdominal pain and GI dysmotility Control group A:

No control group

Control group B:

No control group

Small intestine Average Range Average Range Average Range
57 mast cells/hpf 30-90 mast cells/hpf N/A N/A N/A N/A
Diffuse scattered cells, no clusters.

 

Table 6: Mast cell count in colon of patients with GI pain and dysmotility and a history of allergic disease
Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.
Microscopy method: Magnification not explicitly stated, assumed 400x, mast cells counted in 1 hpf
Visualization: CD117 (IHC)
Sample type Study group: Diarrhea predominant IBS Control group A:

Healthy controls

Control group B:

No control group

Colon Average Range Average Range Average Range
37 mast cells/hpf 1-69 mast cells/hpf N/A N/A N/A N/A
Diffuse scattered cells, no clusters.

 

A 2013 paper quantified mast cells in patients with diarrhea predominant irritable bowel syndrome and compared to healthy controls. The patients averaged 26.2 mast cells/hpf in the jejunum, part of the small intestine, while the controls averaged 17.2. Mast cells were identified using an antibody to CD117, the CKIT receptor found on the surface of all mast cells. The cells were likely counted in only 1 hpf as it was not explicitly stated. Distribution of mast cells was not described. See table 7 for details.

 

Table 7: Mast cell count in small intestine of patients diarrhea predominant irritable bowel syndrome
Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168.
Microscopy method: Magnification not explicitly stated, assumed 400x, number of hpf not explicitly stated, assumed mast cells counted in 1 hpf
Visualization: CD117 (IHC)
Sample type Study group: Diarrhea predominant IBS Control group A:

Healthy controls

Control group B:

No control group

Jejunum Average Range Average Range Average Range
26.2 ± 11.1 mast cells/hpf N/A 17.2 ± 8.8 mast cells/hpf N/A N/A N/A
Diffuse scattered cells, no clusters. Diffuse scattered cells, no clusters.

References:

Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.

Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.

Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168,

Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.

Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.

Ramsay DB, et al. Mast cells in gastrointestinal disease. Gastroenterology & Hepatology 2010; 6 (12): 772-777.

Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gatroenterol 2012; 18 (5): 322-326.

Walker MM, et al. Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia. Aliment Pharmacol Ther 2009; 29 (7): 765-773.

Hahn HP, Hornick JL. Immunoreactivity for CD25 in Gastrointestinal Mucosal Mast Cells is Specific for Systemic Mastocytosis. American Journal of Surgical Pathology 2007; 31(11): 1669-1676.

Vivinus-Nebot M, et al. Functional bowel symptoms in quiescent inflammatory bowel diseases : role of epithelial barrier disruption and low-grade inflammation. Gut 2014; 63: 744-752.

Minnei F, et al. Chronic urticaria is associated with mast cell infiltration in the gastroduodenal mucosa. Virchows Arch 2006; 448(3): 262-8.

Hamilton MJ, et al. Mast cell activation syndrome: A newly recognized disorder with systemic clinical manifestations. J Allergy Clin Immunol 2011; 128: 147-152.

Barbara G, et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology 2004; 126(3): 693-702.

Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.

Afrin LB, Molderings GJ. A concise, practical guide to diagnostic assessment for mast cell activation disease. World J Hematol 2014; 3 (1): 1-17.

Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

Akin C, et al. Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol 2010; 126 (6): 1099-1104.

Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol 2012: 157 (3): 215-225.

 

Mast cells in the GI tract: How many is too many? (Part One)

Let’s have a chat about the idea that 20 mast cells/hpf (high powered field) in gastrointestinal biopsy is higher than normal.

First, let’s review a few things.

The WHO diagnostic criteria for systemic mastocytosis are as follows:

Table 1: World Health Organization Criteria for Systemic Mastocytosis (2008)
  • Systemic mastocytosis is diagnosed in the presence of: 1 major and 1 minor criterion; or 3 minor criteria.
  • Biopsy specimens can be from any non-cutaneous organ (any organ that is not the skin).
Major criterion:
Multifocal, dense aggregates of mast cells (15 or more) detected in sections of bone marrow and confirmed by tryptase immunohistochemistry or other special stains:
Minor criterion:
1.       In biopsy section, more than 25% of mast cells in the infiltrate have atypical morphology, or, of all the mast cells in the smear, more than 25% are immature or atypical. (25% of the mast cells are shaped wrong.)
2.       Mast cells co-express CD117 with CD25 and/or CD2. (Mast cells show markers CD25 or CD2 on their outsides.)
3.       Detection of KIT point mutation at codon 816 in bone marrow, blood or other extracutaneous organs. (Positive for the CKIT D816V mutation.)
4.       Serum total tryptase persistently >20 ng/ml (not a valid criteria in cases of systemic mastocytosis with associated clonal non-hematologic mast-cell lineage disease). (Baseline serum tryptase over 20 ng/ml – baseline, not reaction.)

 

There are several different diagnostic algorithms floating around for mast cell activation syndrome (MCAS).  They are summarized here:

Table 2: Diagnostic algorithms for  mast cell activation syndrome (MCAS, also called mast cell activation disorder, MCAD)
  • Biopsy specimens can be from any non-cutaneous organ (any organ that is not the skin).
Molderings, Afrin 2011 Akin, Valent, Metcalfe 2010 Valent, Akin, Castells, Escribano, Metcalfe et al 2012
MCAD (mast cell activation disease, an  umbrella term including both MCAS and SM) is diagnosed if both major criteria, or one major criterion and one minor criterion, are present; following bone marrow biopsy, diagnosis is narrowed down to either SM or MCAS MCAS diagnosed if all criteria are met MCAS diagnosed if all criteria are met
Major Criteria
Multifocal of disseminated dense infiltrates of mast cells in bone marrow biopsies and/or in sections of other extracutaneous organ(s) (GI tract biopsies; CD117-, tryptase- and CD25- stained) Episodic symptoms consistent with mast cell mediator release affecting ≥2 organ systems evidenced as follows:

  • Skin: urticaria, angioedema, flushing
  • Gastrointestinal: nausea, vomiting, diarrhea, abdominal cramping
  • Cardiovascular: hypotensive syncope or near syncope, tachycardia
  • Respiratory: wheezing
  • Naso-ocular: conjunctival injection, pruritus, nasal stuffiness
Typical clinical symptoms
Unique constellation of clinical complaints as a result of a pathologically increased mast cell activity (mast cell mediator release symptom) A decrease in the frequency or severity or resolution of symptoms with antimediator therapy: H1– and H2-histamine receptor inverse agonists, antileukotriene medications (cysteinyl leukotriene receptor blockers or 5-lipoxygenase inhibitor), or mast cell stabilizers (cromolyn sodium) Increase in serum total tryptase by at least 20% above baseline plus 2 ng/ml during or within 4 h after a symptomatic period
  Evidence of an increase in a validated urinary or serum marker of mast cell activation: documentation of an increase of the marker to greater than the patient’s baseline value during a symptomatic period on ≥2 occasions or, if baseline tryptase levels are persistently >15 ng, documentation of an increase of the tryptase level above baseline value on 1 occasion. Total serum tryptase level is recommended as the marker of choice; less specific (also from basophils) are 24-hour urine histamine metabolites or PGD2 or its metabolite 11-β-prostaglandin F2. Response of clinical symptoms to histamine receptor blockers or MC-targeting agents e.g. cromolyn
  Rule out primary and secondary causes of mast cell activation and well-defined clinical idiopathic entities
Minor Criteria
Mast cells in bone marrow or other extracutaneous organ(s) show an abnormal morphology (>25%) in bone marrow smears or in histologies
Mast cells in bone marrow express CD2 and/or CD25
Detection of genetic changes in mast cells from blood, bone marrow or extracutaneous organs for which an impact on the state of activity of affected mast cells in terms of an increased activity has been proved
Evidence of a pathologically increased release of mast cell mediators by determination of the content of:

  • Tryptase in blood
  • N-methylhistamine in urine
  • Heparin in blood
  • Chromogranin A in blood
  • Other mast cell specific mediators (leukotrienes, PGD2)

 

Additionally, a questionnaire (found here: http://www.wjgnet.com/2218-6204/abstract/v3/i1/1.htm) designed to assess the likelihood of mast cell activation disease (MCAS or SM) in a patient was published in 2014 by Lawrence Afrin.  It assigns numerical values to various findings, such as mediator elevation, symptoms, clinical findings, and biopsy features.

The criteria for systemic mastocytosis can be met with a gastrointestinal biopsy showing the features listed above in Table 1.  So if you have gastrointestinal scopes and your biopsy shows mast cells with the features listed in Table 1, then that contributes to receiving a diagnosis of SM.  If you meet some of the criteria but not all of them, with a GI biopsy or otherwise, then you receive a diagnosis of monoclonal mast cell activation syndrome (MMAS), which is like a pre-SM.

A common adage in the mast cell community is that having 20 or more mast cells in a high powered field (hpf, what you see when you look through a microscope with high magnification) is diagnostic for mast cell activation syndrome.

In 2006, a paper was published called “Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.” This paper detailed a study that quantified the mast cells in biopsies of duodenum (small intestine) and colon in patients with chronic diarrhea that resisted treatment. These counts were then compared to patients who had other conditions that caused chronic diarrhea, and to some control subjects that had no GI symptoms.

Table 3: Average mast cell count per hpf in colon and duodenum (Jakate 2006)
Group Average mast cell count in colon and duodenum
Healthy control group 13.3 ± 3.5
Inflammatory GI disease control group 12.4 ± 2.3
Intractible chronic diarrhea group 25.7 ± 4.5

 

The average mast cell count in the healthy control group was 13.3/hpf.  (See Table 3 for details.) Two standard deviations from this value is approximately 20/hpf.  Two standard deviations (SD) is a statistical mechanism that allows for variation in the patient, sample or test procedure.  It is common to round to an even number.

The patients in this group were not evaluated for typical mast cell symptoms.  No information is provided regarding history of allergic or atopic disease. This paper is the origin of the idea that more than 20 mast cells/hpf in the gastrointestinal tract is considered higher than normal.

 

References:

Jakate S, et al. Mastocytic enterocolitis: Increased mucosal mast cells in chronic intractable diarrhea.  Arch Pathol Lab Med 2006; 130 (3): 362-367.

Akhavein AM, et al. Allergic mastocytic gastroenteritis and colitis: An unexplained etiology in chronic abdominal pain and gastrointestinal dysmotility. Gastroenterology Research and Practice (2012): Article ID 950582.

Martinez C, et al. Diarrhoea-predominant irritable bowel syndrome: an organic disorder with structural abnormalities in the jejunal epithelial barrier. Gut 2013; 62: 1160-1168,

Sethi A, et al. Performing colonic mast cell counts in patients with chronic diarrhea of unknown etiology has limited diagnostic use. Arch Pathol Lab Med 2015; 139 (2): 225-232.

Doyle LA, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014; 38 (6): 832-843.

Ramsay DB, et al. Mast cells in gastrointestinal disease. Gastroenterology & Hepatology 2010; 6 (12): 772-777.

Zare-Mirzaie A, et al. Analysis of colonic mucosa mast cell count in patients with chronic diarrhea. Saudi J Gatroenterol 2012; 18 (5): 322-326.

Walker MM, et al. Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia. Aliment Pharmacol Ther 2009; 29 (7): 765-773.

Hahn HP, Hornick JL. Immunoreactivity for CD25 in Gastrointestinal Mucosal Mast Cells is Specific for Systemic Mastocytosis. American Journal of Surgical Pathology 2007; 31(11): 1669-1676.

Vivinus-Nebot M, et al. Functional bowel symptoms in quiescent inflammatory bowel diseases : role of epithelial barrier disruption and low-grade inflammation. Gut 2014; 63: 744-752.

Minnei F, et al. Chronic urticaria is associated with mast cell infiltration in the gastroduodenal mucosa. Virchows Arch 2006; 448(3): 262-8.

Hamilton MJ, et al. Mast cell activation syndrome: A newly recognized disorder with systemic clinical manifestations. J Allergy Clin Immunol 2011; 128: 147-152.

Barbara G, et al. Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome. Gastroenterology 2004; 126(3): 693-702.

Guilarte M, et al. Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum. Gut 2007; 56: 203-209.

Dunlop SP, et al.  Age related decline in rectal mucosal lymphocytes and mast cells. European Journal of Gastroenterology and Hepatology 2004; 16(10): 1011-1015.

Afrin LB, Molderings GJ. A concise, practical guide to diagnostic assessment for mast cell activation disease. World J Hematol 2014; 3 (1): 1-17.

Molderings GJ, et al. Mast cell activation disease: a concise, practical guide to diagnostic workup and therapeutic options. J Hematol Oncol 2011; 4 (10).

Akin C, et al. Mast cell activation syndrome: proposed diagnostic criteria. J Allergy Clin Immunol 2010; 126 (6): 1099-1104.

Valent P, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol 2012: 157 (3): 215-225.